Surf AlphaData erratic changes

Hi,

I am displaying two intersecting slice from a 3d volume using surf with a slight transparency (Matlab 2021, surf fonction, alphadata parameter).

While I have no issue with the painters renderer any manipulation (rotation,zoom updated of data) is awfully slow.

The OpenGL however gives the impression of changing the alphadata or switch slice focus (looks like a foreground/background switch) depending of the view orientation.

I did not have this issue with anterior version of Matlab (2019b and earlier).

What would cause this issue and is there any solution?

Thank you,

Answer 1

[Rishita]

Alpha value sets the face transparency for objects in the current axes that support transparency. Specify value as 'clear' or 'opaque', or as a number in the range [0, 1]. A value of 0 makes the objects transparent, and value of 1 makes the objects fully opaque.

opengl info prints information about the OpenGL implementation currently in use by MATLAB, such as the version, vendor, and graphics features that it supports. Using this command loads OpenGL. Starting in R2019a, this syntax is no longer recommended. For more information, see Version History.

[Pieromane]

Hello,

thank you for the answer. I found the source of my issue.

The axis display with 'opengl software' (info = rendererinfo(gca) ) instead of the hardware. The opengl software does not seem to be able to display interleaved object properly and an object can not have one part in the foreground and the other in the background.

However, even after switching to 'opengl hardware' (confirmed by opengl info), I am unable to force the axis to use opengl hardware. I checked with anterior version of matlab I am using (2019 a-b) and I do not have this issue.

Thank you,